Over 250,000 patients a year worldwide undergo heart valve replacement. In general, there are two possible choices for replacement heart valves, viz., mechanical or biological prostheses. Biological heart valve prostheses have many advantages over mechanical devices.
Autologous tissue from fresh or cadaveric sources, i.e., human tissue, can be used in the production of biological prostheses (bioprostheses) for human implantation. The shortage of autologous donor material, which presents a supply problem, can be overcome by using alternative sources for tissue, such as animal tissue. To prevent the immunological rejection of animal tissue-derived bioprostheses once they are implanted into a human recipient, animal tissue can be treated using processes such as disclosed in U.S. Pat. Nos. 6,166,184 and 6,509,145; and published U.S. Patent Application Nos. 20030118981A1, 20050020506A 1 and 20050266390A 1.
Despite their many advantages, a major drawback to the use of biological heart valve prostheses is their relative poor durability as compared to the durability of mechanical devices. To enhance the durability of bioprostheses, tissue engineering efforts have been made to produce tissue “scaffolds” that can be regenerated, i.e., recellularized, with host cells once implanted in a recipient.
However, there is still a need in the art for durable, non-immunogenic and viable bioprostheses that are amenable to healing and to growth, for example, in children, as well as a process for preparing such bioprostheses. In addition, there is a need for a process for decellularizing harvested biological (e.g., animal) tissue and extracting antigens from the tissue in order to provide bioprostheses suitable for human use, thus offering a viable alternative to allogeneic donor tissue.